Index: uspace/app/mkfat/mkfat.c
===================================================================
--- uspace/app/mkfat/mkfat.c	(revision 24738df57dd810b249719942514a5398fed438d5)
+++ uspace/app/mkfat/mkfat.c	(revision c80100f087255f791b581e4a31903cbacc0d8487)
@@ -180,5 +180,6 @@
 		printf(NAME ": Block device has %" PRIuOFF64 " blocks.\n",
 		    dev_nblocks);
-		cfg.total_sectors = dev_nblocks;
+		if (dev_nblocks < cfg.total_sectors)
+			cfg.total_sectors = dev_nblocks;
 	}